How would you confirm that a colourless liquid given to you is pure water?

Take a sample of colourless liquid and put it on a stove; if it starts boiling exactly at 100°C, then it is pure water. Any other colourless liquid, such as vinegar, always has a different boiling point. Also, observe carefully that after some time the whole liquid will convert into vapor without leaving any residue. We can check it by checking its reactivity with some metals that react violently with water.